<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>布局</title>
</head>
<style>
  #box{
    /*width: 600px;*/
    /*height: 600px;*/
    background-color: #0bb20c;
    float: right;
  }

  #box > div:first-child {
    width: 200px;
    height: 200px;
    float: right;
    background-color:red;
  }

  #box > div:nth-child(2) {
    width: 200px;
    height: 200px;
    background-color: yellow;
    float: right;
  }

  #box > div:nth-child(3) {
    width: 200px;
    height: 200px;
    background-color: blue;
    float: right;
  }
  #box > div:last-child {
    width: 400px;
    height: 400px;
    background-color: #000005;
    clear: both;
  }
</style>
<body>
    <div id="box">
        <div>1</div>
        <div>2</div>
        <div>3</div>
        <div>4</div>
    </div>
</body>
</html>
